Synthetic RNA molecules containing 2'-o-methylnucleotides at specified regions within the polymer chain will be used as substrates to examine the processing of ribosomal RNA in Novikoff ascites tumor cells. A 3'-terminal specific exoribonuclease from Novikoff cell nuclei will be used with these 2'-o-methylated polynucleotides as a model system for studying the role of 2'-o-methylation in the processing of RNA. The levels and distribution of 2'-o-methylnucleotides in several classes of RNA will be determined for normal rat liver, Novikoff ascites cells, and a carcinogen-induced rat liver tumor. The effect of several carcinogens on RNA 2'-o-methylation and the involvement of this methylation in RNA processing will be studied in vivo using Novikoff cells in tissue culture. Feline leukemia virus RNA, which was shown to contain 2'-o-methyl groups, will be further purified and characterized in an attempt to identify which of the several classes of RNA located within the virion are methylated.